rbarbs wrote:
My mother has a garden which has a fairly substantial slope (as above)
and is thinking of levelling it, and putting a supporting drystone
wall at the bottom (next to the drive). She is concerned about
drainage and cost.

I imagined that the best thing to do would be to clear back the soil,
fill it in with rubble and then put a holey tarp down and relay the
soil?

3 metres drop over 25 metres?
That is a massive amount to fill, probably 50 tonnes of hardcore will be
needed to fill it. For instance, I cleared a raised flowerbed last week,
mainly rubble under 3" of soil. It was under 6 metresx 2 metres x
45cm.So roughly, under 6 square metres (the skip size was 6 yds, and was
almost full) The waste weighed around 4 tonnes.

You will need something substantial at the end to stop it slipping -
caged stones/rocks would be good (gabions), then infill with rubble.It
will need to be compacted well too, so no great big lumps of masonry can
be chucked in.

This is a major undertaking, which would be very difficult to undertake
as a DIY job, just because of the amount of infill and support required.
Alan.

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